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I have a stock 2016 Trek 520 bike and I'm a newbie to road cycling.

  • It has Alivio front derailleur and Deore rear derailleur with Deore triple-chainring crank.

  • The 2016 came with 26/36/48 front chainrings and 9-speed 11-32 cassette. I would like to get it as low as possible by replacing the smallest front chainring from 26 to 22 (while keeping all other components.)

  • Will it work or is this something that I need to experiment with to find out? I'm hoping that someone already tried this and can share their experience.

  • will shifting up/down between 22 & 36 cause a problem? (A difference of 14T instead of the stock 10T)

  • we can assume that I will never ride in the smallest chainring and the smallest 4 rear cogs.

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    If you pedal at 90 rpm, with a 22-tooth chainring up front and the chain on a 32-tooth sprocket on the rear, a 700c bike will be going less than 5 mph/8 kph. That's barely fast enough to stay upright reliably, and it's really tough to maintain a straight course at that low of a speed - to keep your bike upright can require large changes in direction. Can you sustain your pedaling at 90 rpm or higher? – Andrew Henle May 14 at 19:02
  • Thanks for the reply. I do have a cadence sensor and I already tried 26/32 when climbing at 80-85 rpm which came out to about 5.2 mph and it was pretty stable. – Mars2020 May 14 at 21:16
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    @AndrewHenle 22/36 chainset with 11-36 is pretty normal on 29ers. Thats a considerably lower ratio, and still no problems staying upright. – Andy P May 15 at 15:21
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    @Mars2020 26/32 is already a very low gear for road cycling. Typically you'd only go as low as 34/28 or 34/32. I wouldn't take any drastic action changing things, as I think you'll find very quickly you don't need a lower gear – Andy P May 15 at 15:23
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Shimano prides itself on seamless shifting and it's specs are quite conservative to preserve that reputation. With a little sensible caution and a chain catcher you should be able to replace the 26 with a 22. 22/36 is a big drop. If you are just going to replace a single chainring, I'd suggest a 24 rather than 22. When cogs are that small, even 2 teeth is a much smaller gear. 48/36/24 is a very standard touring triple ring config.

If you've got a bit more coin to spend I would highly recommend going to a Deore XT 10 speed triple, it comes with 24/32/42 and can easily be swapped out for your crank and a 22t replacement works just fine. It will work fine with your current 9spd drive train and provide a more reasonable set of gears. I did this with my 2017 Haanjo Exp which has very similar specs.

https://www.ebay.com/p/Shimano-XT-M780-10-Speed-Triple-175mm-24-32-42t-Crankset-With-Bottom-Bracket-MTB/1200053828?iid=192866758545

That price is kind of high IMHO, you should be able to find it cheaper.

Another change you might consider is switching to a 12-36 9 speed cluster in the rear. This will work just fine with your components and provide more usable gears in the middle and high chainrings. The difference between 26/32 and 26/36 will be significant. You'll need to learn what the "B" adjustment is on a derailleur to get this cluster working properly.

https://www.jensonusa.com/Shimano-CS-HG400-9-Speed-Cassette-12-36T?pt_source=googleads&pt_medium=cpc&pt_campaign=shopping_us&pt_keyword=&gclid=EAIaIQobChMIjJOfr-Sd4gIVjbxkCh26UAvIEAQYASABEgLmy_D_BwE

That price is about the same as a 22t chainring and probably the cheapest way to get lower gears on that bike.

With a Wolftooth Roadlink, you can even go as big as 40t in the back with a 9 speed Deore derailluer. Finding a 9 speed cluster with a 40t isn't cheap, but it is possible.

While it's getting better, standard gearing that comes with most bikes makes very little sense for the novice rider. 48/11 is a huge gear and if you've got steep/long hills 26/32 is not low enough to climb w/o going into the red zone. Especially on a touring bike that is meant to carry loads.

There is a point where the gearing gets too low to ride. It depends a lot on the terrain and rider, I found that 22/40 was too low for me even on steep dirt. But having a 24/40 works for me for long fire roads at altitude.

There is a lot to learn and you may outgrow your gears, but the best investment you can make in gear starting out is gears that work for YOU!, not tour de france racers.

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Referencing Shimano's 2016 archive specs docs: https://productinfo.shimano.com/download/?path=pdfs/archive/2015-2016_Specifications_v024_en.pdf

From the specs it's possible to work out the exact crank and derailleurs you must have: Deore FC-M610 crank, Deore RD-M610 SGS rear derailleur, Alivio M4000 front derailleur.

The RD-M610 SGS has a total capacity of 43 teeth. The capacity you current drivetrain needs is (diff largest/smallest sprockets) + (diff largest/smallest chainrings) = (48-26)+(32-11) = 43, so the derailleur will not tolerate a 22 tooth chainring. If you ever change gear to the smaller chainring/sprockets the chain will likely come off the chainrings or sprockets or both, which is a messy pain at best and dangerous at worst.

Additionally, the front derailleur has a capacity of 18 teeth difference between largest and smallest chainrings. 48-22 = 26, so the front derailleur will not accommodate the 22 tooth ring.

If you really want to reduce the gear ratios you really need to replace all three chainrings. The FC-M60 came with 42-32-24 rings as well as 48-36-26, so you could drop down 2 teeth. To get 40-30-22 you need a FC-M612 which has a smaller chainring bolt circle diameter.

  • Thanks for the link to the chart. Here is Trek's official specs archive.trekbikes.com/us/en/2016/Trek/520#/us/en/2016/Trek/520/… but after looking at the chart, I'm not sure the FD is Alivio (even though Trek said it is) as the stock chainring is 26-36-48 (22T difference, largest ring 48 that's not within Alivio specs.). I couldn't find any model # on the RD & FD. – Mars2020 May 14 at 21:11
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    If you can get access to a 22 tooth chainring without buying it, I would test if it works despite technically being out of specc. Shimano is quite conservative. I have been riding with a 26 chainring on a 50/39/30 crank for a year now and don't have problems (except that I cannot shift into all gears). However, this is usually quite bike specific and definitely a hack. – StefanS May 15 at 7:04

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